To cupcake or spend valuable time flirting/charming/fucking/etc with another person. Sifters ignore everything else in the world including family, friends, money, fun, other partners, and in serious cases work. Sifting is a serious condition that should not be taken lightly and should be addressed immediately upon diagnosis.

Berby likes to sift all day and all night, drinking wine with his love.

I tried to get him to go to the city but he said he would be too busy sifting in his bedroom.